Regulatory clearance of radioactive soil and concrete wastes at KAERI

In the radioactive waste storage facilities at the Korea Atomic Energy Research Institute (KAERI) in Daejeon, there are about 4,800 drums of radioactive contaminated soils and concretes wastes. As the storage facility is scheduled to be saturated in 2014, to secure the storage capacity and to reduce the disposal cost and management cost, the volume of the soil and concrete wastes should be reduced. Because the soil and concrete wastes have been stored since their generation in 1988, the radioactivity concentration of the wastes must have decayed a lot. So, regulatory clearance can be an option for the treatment of the soil and concrete wastes. For the treatment, radioactivity concentrations of all the wastes in 200 liter drums were analyzed first. The analysis result shows that the major radionuclides in the wastes were Co-60 and Cs-137. In addition to that, it was analyzed that about, 1,100 drums of concrete and about 1,800 drums of soil have a total radioactivity concentration less than 0.1 Bq/g which was recommend by the IAEA as a clearance criteria. And for a disposal scenario, it was assumed that the cleared wastes are disposed in a publically reclaimed landfill. Using the parameters for the assumed scenario, the radiological dose was estimated using the RESRAD code. According to the estimation result, individual dose and collective dose were 4.55E+0 micro-Sv/yr and 1.37E-5 man-Sv/yr for disposal work and 1.00E-2 micro-Sv/yr and 3.00E-7 man-Sv/yr for workers at reclaimed landfill after disposal. These result meet the criteria set by the Atomic Energy Act of Korea (individual dose <10 micro-Sv/yr and collective dose <1 man-Sv/yr). It can be concluded that the regulatory cleared soil and concrete wastes can be disposed in the publically reclaimed landfill safely. The result of this study can be applied to other regulatory clearance activities in Korea. (author)